Latitude & Longitude

This is another lesson focusing on an introductory concept that will continuously be "looped in" to future study. Coming into Earth Science as 9th graders, my students haven't been exposed to the concepts of latitude and longitude on any level, so it's both helpful and necessary to provide the proper context for understanding the coordinate system. 

As a general note, many students frequently struggle to actually differentiate between latitude and longitude - they end up confusing the terms. Enough practice, careful planning (i.e. making sure that latitude is always written first in any coordinate system) and execution, and a mnemonic technique or two generally ameliorate this problem. Quickly, I have two ways (you may have others) to help them remember: I tell them that the "lat" in latitude rhymes with "flat". So "lat" "flat" is an effective way to remember that latitude lines go from left to right (parallel to the Equator). Another quick teaching method is to use the crossing of the "t"s in latitude as a physical reminder of a latitude line. 

There are additional and differentiated ways to teach this (i.e. I've had students label and cut fruits before), but I actually feel that this information is relayed most efficiently in a pictoral sense. Not only will they frequently "see" latitude and longitude lines that way, but they get a better picture of a the scale of latitude and longitude lines in seeing them represented in both a world and area map.

[Note: For embedded comments, checks for understanding (CFUs), and key additional information on transitions and key parts of the lesson not necessarily included in the below narrative, please go to the comments in the following document: 2.2 - Latitude & Longitude (Whole Lesson w/comments). Additionally, if you would like all of the resources together in a PDF document, that can be accessed as a complete resource here: Latitude & Longitude (Whole Lesson)[PDF]. Finally, students may need their Earth Science Reference Tables (ESRT) for parts of the lesson (a document used widely in the New York State Earth Science Regents course) as well.]

Students come in silently and complete the (attached) Do Now. After time expires (anywhere from 2-4 minutes depending on the type of Do Now and number of questions, although this one can be done in about two minutes), we collectively go over the responses (usually involving a series of cold calls and/or volunteers), before I call on a student and ask them to read the objective out loud to start the lesson.

As a general note, the Do Now serves a few purposes:

1. It serves as a general review of the previous day's material;
2. It is a re-activation of student knowledge to get them back into "student mode" and get them thinking about science after transitioning from another content area or alternate class;
3. as a strategy for reviewing material students have struggled with (for example, using this as a focused review for material that they have struggled with on unit assessments or recent quizzes); and,
4. It is an efficient and established routine for entering the classroom that is repeated each day with fidelity (I never let students enter the classroom talking. While it may seem potentially severe to have students enter silently each day, this is both a school wide expectation and a key component of my classroom. In many respects, I find that students readily enjoy the focus that starting with a quiet classrooms brings each day).

I usually introduce this lesson by comparing the coordinate system of latitude-longitude to the streets of New York City. As my students are all from New York, they generally are familiar with the system of streets and avenues, which very closely mirror the lines of latitude and longitude that are introduced in the lesson (Note: This part of the introduction is not contained in the handout). I usually start by asking: "What would you do if you needed to get to my favorite restaurant in Manhattan? What if I said it was on 54th street between 2nd and 3rd Avenue? Could you get there on the subway? [Generally students respond affirmatively]. Just like there's a system of numbered streets and avenues in the city to help you find your way around, the Earth is divided using a similar system - we call them lines of latitude and longitude."

After this brief introduction, I use a group reading strategy ("Control The Game") to have students collectively read the brief passage explaining and differentiating between latitude and longitude. I briefly have students stop to annotate the text and/or to ask a clarifying question or check for understanding, but the important concept to focus in on here is the conceptual framework of what latitude and longitude actually is. The notion that it is an angular measurement is sometimes difficult for students to grasp. Often, an actual object helps - this year, I cut up an apple to show them that the Equator is actually zero angular degrees above the mid-point of the Earth, while the North or South Pole formed a 90 degree angle when measured against the same mid-point. Longitude is measured in the same way, although the Prime Meridian is more of an arbitrary mid-point than the Equator (Note: While interesting, I don't really think it's necessary or practical to get into an extended conversation or discussion about the history of the Prime Meridian here). I also, as explained in the Lesson Introduction above, generally focus in on a few memory tricks to help them differentiate between lines of latitude and longitude.

[Note: For specific annotations/CFUs in the text, consult the annotated Word document in the 'Lesson Introduction' section]

I start this section by modeling how to find the latitude and longitude on a World Map. When teaching this, I try to follow these guidelines:

• Make sure the latitude is always written first! Find the latitude, then the longitude, and always include a North/South designation (unless it's the Equator).
• On this map, be careful in modeling with students using the longitude lines. They alternate by 15 degrees (which is standard on a world map), but are only designated with labels every 30 degrees. I've found that some students can get confused by this, so it may be okay to just note this up front. 
• I am very careful in my modeling with the "visual estimation" component. If a point is not exactly on a line of latitude or longitude, be direct in modeling how you want this to look. I usually do a mini "think aloud" and walk them through how I visually estimate the coordinates. 

As a note on the World Map resource, I directly (as an "I do") model the first 1-2, and then do the next 1-2 as a guided practice, with much more student input. I then have them transition to do 1-2 more, check with a partner, and finish up the rest independently. As a final note, some of the later problems are a bit challenging, so you may want to effectively preview that with your classes as they get closer to tackling them. 

In the Area Map section, I use one based off of New York State in the Earth Science Reference Tables (attached below for reference). If you're using this in another state, you can definitely continue to use the same map of NYS provided, or you can find an additional state or area map on Google to utilize. Ultimately, the important thing to note here is that the latitude and longitude lines are "farther apart" due to the map's scale - students should get experience working with finding coordinates that are more precise than cities on a world map. In this section, I also introduce the notion of minutes (as a further extension, you could even get into seconds) as a way to get more precise coordinates. 

After guiding them through the first example, I usually allow them the opportunity to try the remainder of the practice problems independently before moving on to the exit ticket. 

In this last section of the lesson, students are given independent work time to complete the Exit Ticket. Given the number of questions, they only need about 4-5 minutes, after which it is graded communally, with a key emphasis on particular questions and items that hit on the key ideas of the lesson. We then usually quickly wrap up in the same fashion - I give students time to pack up their belongings, and I end the class at the objective (which is posted on my whiteboard, in addition to being on their 'Do Now' at the start of each lesson) and ask students two questions:

1. Do you feel that you mastered the objective for the day?
2. Can you reiterate one thing you learned about ____________ (in this case, determining lines of latitude and longitude, etc.)

When the bell rings, students are asked to stand, push in their chairs, and exit the room.